As the related art, JP-A-2000-116074 discloses an example of a laminated core that includes: a first core member formed by sequentially arranging core pieces, each of which has a back yoke portion, a magnetic-pole teeth portion protruding from the back yoke portion, an arc-shaped convex portion provided to one end of the back yoke portion, an arc-shaped concave portion provided to the other end of the back yoke portion, and a rotation shaft portion provided to the arc-shaped convex portion, in such a manner that the arc-shaped convex portion and the arc-shaped concave portion of adjacent core pieces fit and abut against each other; and a second core member formed by sequentially arranging the core pieces in a direction opposite to the arrangement direction of the first core member in such a manner that the arc-shaped convex portion and the arc-shaped concave portion fit and abut against each other, and the first core members and the second core members are stacked alternately and connected to each other. The laminated cores formed by stacking core pieces are connected to each other in a rotatable manner about the rotation shaft portions.
The fit-abutting portions of the arc-shaped convex portion and the arc-shaped concave portion of the adjacent core pieces are formed by punching and lancing inside a die as is disclosed in JP-A-2002-171725.